Crystal structure of zinc(II) hydrated trinuclear complex with monoprotonated ethylenediaminetetraacetate anion(3−), [Zn3(HEdta)2(H2O)6

Abstract

The crystal structure of the [Zn{sub 3}(HEdta){sub 2}(H{sub 2}O){sub 6}] complex (I) is determined by X-ray diffraction analysis. The crystals are orthorhombic, a = 14.780 A, b = 29.699 A, c = 7.032 A, Z = 4, and space group Pna2{sub 1}. The structural units of crystals I are trinuclear linear molecules, in which the peripheral atoms Zn(1) and Zn(2) each coordinate two N atoms and three O atoms of the HEdta{sup 3-} ligand and the O(w) atom of the H{sub 2}O molecule, whereas the central Zn(3) atom coordinates four O(w) atoms of the H{sub 2}O molecules and two terminal O atoms of the two HEdta{sup 3-} ligands. The HEdta{sup 3-} ligand fulfills a hexadentate chelating-bridging function. The bond lengths are as follows: Zn-O(HEdta), 2.006(4)-2.123(4) A; Zn-N, 2.214(6) and 2.128(5) A; and Zn-O(w), 2.006(6)-2.225(5) A. In structure I, there is a specific contact formed by hydrogen bonds, owing to which the distance between the central atoms of individual molecules appears to be shorter than that in covalently bonded complexes.